function check_form(){
    old_pwd = document.getElementById('old_user_pwd');
    if(old_pwd.value==''){
            return false;
    }
    user_pwd = document.getElementById('user_pwd').value;
    config_user_pwd = document.getElementById('config_user_pwd').value;
    if(user_pwd!=config_user_pwd){
            alert('Not match!');
            return false;
    }
    return true;
}
